Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Met > Definition of relative humidity > Flashcards

Definition of relative humidity Flashcards

1
Q

What are the typical weather conditions in a westerly situation?

A

Very changeable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where is the core of the polar front jet stream found?

A

In the tropical air mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

At what geographic latitude are prevailing westerlies found

A

40-60 // average 50

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

In a low pressure system, convergence at the surface is caused by

A

Frictional forces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What can favour the development of frontal fog?

A

Increase of relative humidity by evaporation of rain drops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What weather would you expect from a cold front?

A

Initially lifts warm air causing thunderstorms and CB clouds. Pressure drops then rises. After front passes, cool temperatures and clear or mild sky

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Occluded front weather

A

There is often precipitation from CB and NS clouds. Wind changes direction as front passes and temp changes. Usually dry and clear skies after it passes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The easterly jet is a jet stream that occurs

A

Only in the summer of the northern hemisphere at approximately 45000 feet when the ITCZ is at it’s most northerly position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Insolation as at a maximum at

A

local noon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Clear ice is forms by

A

supercooled drops hit the aircraft and slide back on the airframe, freezing slowly. Hard to remove and hazardous. 0’ to -15’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Rime Ice

A

Freezes on impact, thick frost appearance. -10° to -20°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Mixed ice

A

Mixture of rime and clear. -10° to -15°

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Hoar frost

A

When body of aircraft is very cold and freezes ambient moisture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How to avoid high concentrations of ice crystals

A

Plan ahead and fly in UPWIND direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe trade winds

A

Low level wind system between subtropical high pressure belt and the equatorial trough of low pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does lightning affect aircraft?

A

Can cause some structural damage. Aircraft can become a charge carrier and initiate an electrical discharge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is a cold air drop?

A

A low pressure area with colder air compared to its surroundings. It can be found on upper contour charts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Water vapour condensing into water (heat) -

A

Releases large amounts of latent heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

The cloud sequence of approaching warm front

A

CI, CS, AS, NS, ST

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What wind change is expected in northern hemisphere when descending to surface?

A

Backing ca. 30 degrees, speed is reduced by ca 50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Divergence over a uniform surface is caused by:

A

Frictional force + anticyclonic curvature of the isobars

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How can orographic fog be dissipated?

A

Downslope wind

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The ITCZ is further North or South in summer?

A

Further north in summer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

In towering cumulus clouds, what features does the cloud have in terms of vertical wind and temperature in relation to the environment

A

Strong updraughts occur and temperature inside the cloud is higher than surrounding areas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Furthest north ITCZ reaches in summer is ?

A

China

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Characteristics of the Bora are?

A

Cold and strong wind that blows in winter towards the Adriatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What happens physically in a warm occlusion?

A

The warm air is lifted

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Where are easterly waves most likely to form?

A

In the trade wind zones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What temperatures would you expect the worst icing effects?

A

between -20°C and -30°C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Cumulonimbus cloud with clearly defined anvil is:

A

Capillatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

A blocking anticyclone in the northern hemisphere is:

A

A quasi-stationary, warm anticyclone situated between 50°N and 70°N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Area of thermal low pressure is formed by:

A

A temperature rise in an area in relation to the environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What could be said about the height of a polar front jet stream core

A

It lies at a height where there is NO horizontal temperature gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

When is latent heat absorbed?

A

Changing from solid to liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the role of the World Area Forecast Centre (WAFC)

A

A meteorological centre that provides real-time meteorological information broadcasts for aviation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Does the wind veer or back upon the passage of a front in the northern hemisphere?

A

Veers when front passes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Depressions associated with developing frontal waves move in the direction of the 3000 feet wind in

A

The warm sector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

The height of the lifting condensation level is determined by :

A

The temperature and dew point at the surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is classed as a low level cloud?

A

SC (stratocumulus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

A parcel of rising air rises through an isothermal layer. What happens to the temperature?

A

It remains constant

41
Q

How do you recognise a cold air pool?

A

As a low pressure area aloft (e.g on the 500 HPA chart)

42
Q

What weather would you expect a foehn wind to bring in the Northern Alps?

A

Turbulence during south foehn

43
Q

What would you expect if a cold surface is covered by a warm air mass?

A

A ground inversion will develop

44
Q

What weather is encountered during summer, over land, in the centre of a cold-air drop?

A

Showers and thunderstorms

45
Q

A Foehn wind occurs on the:

A

Leeward (downwind) side of a mountain range and is caused by significant moisture loss by precipitation from cloud

46
Q

Why are there few or no clouds in high pressure areas?

A

Due to subsiding winds

47
Q

What weather phenomenon is created by valleys and mountain slopes?

A

Valley inversions

48
Q

The weather behind a cold front is typically

A

Cu cloud, noticeably colder and drier than the air in front

49
Q

What type of cloud seen from long distance could indicate a tropical revolving storm

A

Dense CI

50
Q

How long does a typical frontal depression last in Europe?

A

7-10 days

51
Q

An isohypse (contour) indicates

A

The true altitude of a pressure level

52
Q

Regarding jet stream turbulence, the strongest CAT is expected to be found on :

A

The cold air side of the pool

53
Q

What type of frozen precipitation with a diameter of less than 4mm can be used in a METAR?

A

Ice pellets

54
Q

Evaporation absorbs or releases heat?

A

Evaporation absorbs heat

55
Q

Define a “HIGH”

A

An area of higher pressure than that of the horizontal environments

56
Q

Pressure compared to sea level formula

A

FL200 = 50%

FL400=25%

57
Q

Frontal thunderstorms are mainly associated with:

A

Cold fronts

58
Q

At which latitudes are you most likely to find the subtropical high pressure belt?

A

Sub-tropical highs are centred at around 25°-35°

59
Q

Rainy seasons in equatorial Africa

A

March to May and October to November

60
Q

The predominant pressure systems in the North Atlantic during summer are:

A

Azores High and Weak Low over NE Canada

61
Q

Prevailing winds in coastal West Africa are

A

SW monsoon in summer and NE trade winds in winter

62
Q

The Harmattan is:

A

NE wind affecting NW Africa during November to April which causes reduced visibility due to dust

63
Q

A trough near the surface is an area of ? pressure and ? features :

A

Convergence and widespread ascent

64
Q

Under anticyclonic conditions in the northern hemisphere, with curved isobars the speed of the gradient wind is :

A

Greater than the geostrophic wind

65
Q

What change of state RELEASES latent heat?

A

Liquid to solid

66
Q

The family of medium clouds include altos and nimbostratus. Where would you expect their height of base to range from?

A

6500 - 23000 feet

67
Q

The main icing zone in the ITCZ is between FL:

A

FL 160 - FL260

68
Q

In wintertime, stratus is often formed when warm maritime air moves over cold land. How could this cloud be classified?

A

Turbulence cloud

69
Q

The RVR reported in the METAR is always the:

A

Value representative of the touchdown zone

70
Q

What weather would you expect BEHIND a cold front?

A

Scattered cloud cover and showers

71
Q

Where do the trade winds blow?

A

Between the horse latitudes and the doldrums

72
Q

What type of weather does coalescence produce in mid latitudes?

A

Drizzle or light rain

73
Q

Coalescence definition:

A

Colliding of rain drops

74
Q

When a cold front passes a chain of mountains, it’s activity

A

Strengthens upwind of the mountains

75
Q

Tropical storm affecting North Australia is called ? and occurs in ?

A

Cyclone and occurs December - April

76
Q

In which stage of a thunderstorms life cycle do up draughts and downdraughts occur simultaneously?

A

Mature Stage

77
Q

STATEMENT - Cold air over warm sea can provide lifting action for air mass T-storms

A

STATEMENT - Cold air over warm sea can provide lifting action for air mass T-storms

78
Q

Snow grains fall from :

A

Stratus or supercooled fog

79
Q

What type of cloud is associated with snow showers?

A

Cumulus or Cumulonimbus

80
Q

The main substance in cirrostratus clouds is :

A

Ice Crystals

81
Q

Most tornadoes have wind speeds of :

A

20 - 40 Knots

82
Q

What units are used to report vertical windshear?

A

KT/100ft

83
Q

Thunderstorms are NOT usually associated with :

A

Warm fronts

84
Q

Describe a warm occlusion in terms of relative position of warmest and coldest air

A

The coldest air mass is AHEAD of the original warm front

85
Q

What climate type is to be expected at 10N - 20N (equatorial)

A

Tropical rain climate

86
Q

The typical weather conditions affecting Darwin in July is?

A

Dry season, mainly SE winds and visibility reduced by haze and dust

87
Q

Which jet would affect a flight from around UK to India during January?

A

Sub-tropical westerly jet with wind speeds exceeding 90 knots

88
Q

When is the term CAVOK used?

A

Visibility of 10KM or more, no clouds below 1500M (5000ft) and no CU clouds or anything of significance

89
Q

What is a VOLMET broadcast?

A

Repetitive voice broadcast including METAR, TAF SPECI and SIGMET

90
Q

What type of cloud can give freezing rain?

A

NIMBOSTRATUS, especially in advance of a warm front

91
Q

What is a downburst?

A

Concentrated downdraught with High speeds and LOWER temperature than surrounding air

92
Q

System that REDUCES in intensity with increasing height must be :

A

Cold and high pressure as it is concentrated at lower levels

93
Q

Characteristics of a warm occlusion in terms of air being warmer/colder behind/in front of the warm sector

A

Air behind the occlusion is WARMER than air in front

94
Q

Up to what FL can one expect mountain waves?

A

FL 600

95
Q

What imaging can be used to detect top of cumulonimbus clouds?

A

Visual and infra red imaging

96
Q

Most likely weather as a warm front passes is :

A

Moderate continuous rain, intermittent light drizzle

97
Q

Where is the source of the southwest monsoon?

A

The southern hemisphere

98
Q

What could be said about nimbostratus clouds and their tendency to extend into multiple layers?

A

It IS possible for NS clouds to extend into more than one layer

99
Q

A possible trigger for an air mass thunderstorm is:

A

Intense insolation of a land surface in the area of a col or a weak low

Met (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions